The Suzuki coupling reaction provides an efficient process for joining arenes (aryls and/or heteroaryls) in the presence of a palladium catalyst (see, e.g., N. Miyaura et al., Synthetic Communications 11: 7, 51-519 (1981); and N. Miyaura et al. Chem. Rev. 95: 2457-2483 (1995). In the Suzuki reaction, a haloarene is reacted with an areneboronic acid in the presence of Pd catalyst and base to form a biarene product. The reaction can also be carried out using areneboronic esters instead of areneborate acids.
WO2009074812 describes a Suzuki couplings using an areneborate ester, that is, 1-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridin-2(1H)-one. WO2009/017664, WO2009/134400, WO2009/017671, and WO2010/011314 also describe Suzuki couplings using areneborate esters including pyridylborate esters to prepare compounds useful for treating metabolic disorders such as diabetes.
WO2009/017664, WO2009/134400, WO2009/017671, and WO2010/011314 describe Suzuki coupling reactions using a reagent of formula (HO)2B-Cy2, where Cy is described as aryl, heteroaryl, cycloalkyl or heterocyclyl. The references also describe compounds where Cy is pyridine and oxo-pyridine.
However, Applicants are unaware of any 2-oxo-1,2-dihydropyridin-4-ylboronic acid derivative where the pyridine nitrogen atom is substituted by an alkyl or cycloalkyl. Such compounds are useful for making compounds in which a 2-oxo-1,2-dihydropyridine derivative is coupled to an aryl or heteroaryl ring at the 4-position of the pyridine.